Preheat oven to 425˚F. Cut chicken breast in half lengthwise so you have 8 thin chicken cutlets. Pound each cutlet in a quart sized ziploc bag or between 2 sheets of plastic wrap into 1/8" thick cutlets. Season both sides of chicken with garlic salt and black pepper.

Spoon and spread 1 Tbsp pesto in the center of each cutlet, top with 2 thin tomato slices and sprinkle with 2-3 Tbsp mozzarella cheese. Roll the chicken up tightly and seal ends with a toothpick.

Preheat large oven-safe skillet over medium/high heat with 1 Tbsp oil and 1 Tbsp butter. Add chicken roll-ups and sear on both sides until golden (4 min per side or 8 minutes total on the stove).

Sprinkle tops with remaining cheese and 1 cup of cherry tomatoes. Place the skillet on the center rack of oven and bake 425˚F for 13-15 minutes (13 min for these these medium chicken breasts and 15 min for larger chicken breasts, or until internal temp of chicken reaches 160˚F on instant-read thermometer.